Freestyle depth of field
Freestyle is applied after the actual render, so the short answer is: no, you have to work with post processing (maybe filtering the freestyle edges with a Kirsch filter and apply the blur only to that portion of the image). 

But, you might be able to fake something using the "Distance from camera" modifiers in freestyle. This modifier can be applied to color, alpha and thickness. The settings are under line style - here is a quick example: